GaAs tunnel junction grown using tellurium and magnesium as dopants by solid-state molecular beam epitaxy

Gan, XingYuan; Zheng, Xin; Wu, Yuanyuan; Lu, Shulong; Yang, Hui; Arimochi, Masayuki; Watanabe, Tomomasa; Ikeda, Masao; Nomachi, Ichiro; Yoshida, Hiroshi; Uchida, Shiro

doi:10.7567/jjap.53.021201

Cited by 8 publications

(9 citation statements)

References 29 publications

(31 reference statements)

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“…6 e). A decrease in carrier concentration with an increase in GaTe cell temperature is consistent with the variation of the carrier concentration with Te flux reported 59 , 60 in GaAs thin films, where carrier concentration peaks at 2–3 × 10 19 cm −3 and reduces with further increase in dopant incorporation.…”

Section: Resultssupporting

confidence: 87%

“…At a higher GaTe cell temperature of 570 °C used in our work, a decrease in carrier concentration is observed. The Te induced defects have often been cited 59 to be the cause for the reduction in carrier concentration at higher doping incorporation in thin films. However, the high surface to volume ratio in the one-dimensional NWs, the observed decrease in NW aspect ratio, the combination of both the high growth temperature of 590 °C along with high Te flux at a higher GaTe cell temperature of 570 °C, strongly suggests Te segregation is more likely the cause for the carrier concentration decrease.…”

Section: Resultsmentioning

confidence: 99%

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A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM

Ramaswamy

Devkota

Pokharel

et al. 2021

Sci Rep

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We report the first study on doping assessment in Te-doped GaAsSb nanowires (NWs) with variation in Gallium Telluride (GaTe) cell temperature, using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), conductive-atomic force microscopy (C-AFM), and scanning Kelvin probe microscopy (SKPM). The NWs were grown using Ga-assisted molecular beam epitaxy with a GaTe captive source as the dopant cell. Te-incorporation in the NWs was associated with a positive shift in the binding energy of the 3d shells of the core constituent elements in doped NWs in the XPS spectra, a lowering of the work function in doped NWs relative to undoped ones from UPS spectra, a significantly higher photoresponse in C-AFM and an increase in surface potential of doped NWs observed in SKPM relative to undoped ones. The carrier concentration of Te-doped GaAsSb NWs determined from UPS spectra are found to be consistent with the values obtained from simulated I–V characteristics. Thus, these surface analytical tools, XPS/UPS and C-AFM/SKPM, that do not require any sample preparation are found to be powerful characterization techniques to analyze the dopant incorporation and carrier density in homogeneously doped NWs.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM

Ramaswamy

Devkota

Pokharel

et al. 2021

Sci Rep

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“…We used solid source MBE and coevaporation from a GaTe source during growth. Although Te is well known to be volatile, we demonstrate highly efficient doping in NWs grown at 580 °C and up to 640 °C, i.e., at temperatures well above those used to dope epitaxial layers (535 °C or lower) . Higher growth temperatures allow the achievement of better electrical and optical properties, thanks to the reduction in the residual impurity incorporation.…”

Section: Introductionmentioning

confidence: 99%

“…at temperatures well above those used to dope epitaxial layers (535 °C or lower). [6,19,20] Higher growth temperatures allow the achievement of better electrical and optical properties, thanks to the reduction in the residual impurity incorporation.…”

Section: Introductionmentioning

confidence: 99%

A Roadmap for Controlled and Efficient n‐Type Doping of Self‐Assisted GaAs Nanowires Grown by Molecular Beam Epitaxy

Orrù

Repiso

Carapezzi

et al. 2016

Adv Funct Materials

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N‐type doping of GaAs nanowires has proven to be difficult because the amphoteric character of silicon impurities is enhanced by the nanowire growth mechanism and growth conditions. The controllable growth of n‐type GaAs nanowires with carrier density as high as 1020 electron cm−3 by self‐assisted molecular beam epitaxy using Te donors is demonstrated here. Carrier density and electron mobility of highly doped nanowires are extracted through a combination of transport measurement and Kelvin probe force microscopy analysis in single‐wire field‐effect devices. Low‐temperature photoluminescence is used to characterize the Te‐doped nanowires over several orders of magnitude of the impurity concentration. The combined use of those techniques allows the precise definition of the growth conditions required for effective Te incorporation.

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“…The detailed growth and tunneling properties of the tunneling junction have been reported elsewhere. [21] In the present work, the photovoltaic response of GaInP/GaAs tandem solar cells using the Te/Mg tunnel junction is investigated in detail. The GaInP/GaAs tandem solar cells which are interconnected by this TJ show a high shortcircuit current density of over 12 mA/cm 2 but have a comparatively low open-circuit voltage (V oc ).…”

Section: Introductionmentioning

confidence: 99%

GaInP/GaAs tandem solar cells with highly Te- and Mg-doped GaAs tunnel junctions grown by MBE

et al. 2015

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We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction (TJ) with using tellurium (Te) and magnesium (Mg) as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy (MBE) at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 mA/cm2, but a low open-circuit voltage range of 1.4 V∼1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy (SIMS) analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended GaAs n++/p++ junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of ∼ 2.5 × 1020 in GaAs could cause a lattice strain of 10−3 in magnitude and thus a surface roughening, which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell.

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GaAs tunnel junction grown using tellurium and magnesium as dopants by solid-state molecular beam epitaxy

Cited by 8 publications

References 29 publications

A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM

A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM

A Roadmap for Controlled and Efficient n‐Type Doping of Self‐Assisted GaAs Nanowires Grown by Molecular Beam Epitaxy

GaInP/GaAs tandem solar cells with highly Te- and Mg-doped GaAs tunnel junctions grown by MBE

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